Containers formed from injection molded plastic are widely used for storage and disposal of solid and liquid materials. Such containers generally have a body having a base portion and a set of walls, together defining an interior space for storage of material, with an opening defined by the top edges of the walls. The base may be flat or curved. The walls may have various configurations. The walls generally extend vertically upward from the base, sometimes at an angle so that the horizontal cross-sectional area increases from the base to the top. The horizontal cross-section may be circular or oval, or may be closer to rectangular or square, although generally with the corners being smoothed.
In order to prevent animals from getting at the material stored in the interior region, such containers generally have a lid that is configured to cover and seal the opening. A simple lid may use a friction fit to attach it to the upper edges of the walls. In some cases the lid may be attached to the rear of the walls by a mechanism that allows the lid to rotate about the attachment point so it can move from a closed position in which the opening is sealed to an open position in which the lid is detached from the walls and the lid is substantially spaced apart from the front portion of the walls.
In many areas, a friction fit lid is not sufficient to protect the contents from animals, such as raccoons. Various latching mechanisms have been disclosed to provide a better solution. However, most require a concerted effort by a person in order to unlock the lid. While this is fine for the person putting trash into the container, in some cases it is desirable to use automated systems to pick up the material in the container. Such systems typically employ a pair of lifting arms that extend from a garbage truck and partially surround and squeeze the walls of the container on opposing sides. By squeezing with sufficient force, the arms can hold the container firmly, and the system can automatically lift the container, turning it over and dumping the contents into the truck—as long as the lid is not latched or otherwise held closed. When normal latched containers are used, the driver, or a second person, must get out of the truck and unlatch the lid before the lifting arms grab the container, thus increasing the time and cost for garbage pickup.
Some approaches to addressing this problem have been disclosed but they are complex and expensive and are generally only feasible for industrial scale waste management. For example, locks that automatically unlock due to the force of gravity when the container has been inverted have been disclosed. These are expensive, and also tend to be difficult for a person to use manually when putting trash into the container. Another approach uses a customized container and lifting arms, where the container has a latch on the front side, and the lifting arm has a special mechanism that moves in a pre-defined manner while the container is being picked up specifically in order to open the latch. This is an expensive approach. It would be much preferable to provide a design that allows existing lifting arms to automatically unlatch the lid.